Over the years, there have been numerous variations of locking devices for a multitude of applications. Typically, a locking device is used to secure objects together, whether it be two independent items, a door for an enclosure, or the like. Moreover, a wide variety of locking mechanisms have been employed, including key actuated locks and combination locks, all of various constructions.
A widely used locking device is known as a padlock. The prior art padlock works adequately for a number of conventional applications wherein the span of objects to be secured is relatively short or where the span can be fitted with a hasp. However, numerous shortcomings of padlocks become apparent when a padlock is sought to be used in applications wherein two objects of thick cross-sections are to be secured. Examples of such conventional applications include those where telescopically joined round or square tubing members need to be secured together. Another example is where perpendicular or axially cross-bolting of gates and doors require a substantially rod-like locking device.
As a result of the need for rod or elongated shackle locking devices, various devices have been developed to penetrate multiple surfaces having aligned through bores for the purpose of securing those objects together. Once such example is found in U.S. Pat. No. 2,677,261 issued May 1954 to Jacobi. In the Jacobi patent, a complex locking device is taught in order to prevent actuation of a refrigerator door handle. Another example of a rod locking device is found in U.S. Pat. No. 4,576,021 issued Mar. 18, 1986 to Holden. Holden discloses a locking rod device having a rectangular locking head that is somewhat bulky and non-symmetrical. In the Holden locking device, a radially extendable locking pin engages a circumferential opening in the latch portion of the shackle in order to retain the shackle and locking head together. The bulky nature of this lock head design, however, makes it disadvantageous in use where only limited space is available.
Several additional types of straight shackle locks have been developed wherein the latched portion of the shackle is threadably received in a screw-type lock. Examples of these locks are described in U.S. Pat. No. 4,619,122 issued Oct. 28, 1986 to Simpson as well as in U.S. Pat. No. 4,711,106 issued Dec. 8, 1987 to Johnson. These types of locks, however, tend to be inconvenient and cumbersome to use due to the threaded nature of their locked mechanisms. Specifically, the key actuable locking head described in these two patents require a large number of key rotations in order to thread and fully secure the locking head portion onto the straight shackle. The inconvenience and difficulty of threaded lock systems is compounded when the lock is located in tight or difficult to access areas. Further, the threaded screw lock is especially prone to corrosion and seizure due to the small dimensioning of the threads.
Accordingly, there remains a need for improved locking structures of a rod or cable type nature that can effectively lock objects together. There is a need for such locking mechanisms to have suitable seals and protective structures to prevent ingress of unwanted substances, such as dirt and moisture, into the locking mechanism. There is a further need for locking structures that reduce the tendency for false locking conditions. These conditions are particularly true in the case of trailer hitch locks that utilize linear pins or shanks to connect a draw bar to the trailer hitch receiver inasmuch as these types of hitch locks are continuously exposed to dirt, soil, road grime and the like.
Consequently, my prior U.S. patent application referenced above is designed to meet the aforementioned situations and problems. However, as in the case of trailer hitch units and locks, there are a number of different size units available on the market depending on the size of the rig being towed. Moreover, there are numerous other lock applications which utilize linear pin and shank locks that incorporate shanks having different diameter sizes for different situations. As a result, a number of different locking devices having different sized shanks are needed to meet varied particular applications. This is cumbersome and expensive. Therefore, there is a need for a locking mechanism using a linear shank that is convertible for various applications. In this manner, a single locking unit may be used for a number of varied size locking requirements, such as where the apertures in the units to be connected and locked are varied from application to application.